Joint blender



1955 H. T. BORGSTROM 2,725,740

JOINT BLENDER Filed July 5. 1952 A' L I. I

IN V EN TOR.

ERBEQT T. 802651120 BY United States Patent JOINT BLENDER Herbert T. Borgstrom, Boonton, N. J.

Application July 3, 1952, Serial No. 297,127

2 Claims. (Cl. 72136) This invention relates to a tool adapted to blend a cementitious joint between adjacent structural panels.

In the building industry, the use of pre-formed panels of plaster board and like material, as a substitute for a wet wall construction, has become more and more widespread.

When panels of the character referred to are erected, a joint of approximately one-fourth inch is left between the adjacent edges of adjacent panels, and a joint cement is applied to said joint, said cement usually being employed in conjunction with a perforated tape overlying the space between the adjacent panels.

It is customary, in the industry, to use a joint finishing blade, for the purpose of imparting a transverse convexity to the cementitious joint, throughout the length of the joint. Thereafter, when the joint hardens, it is sanded down and on completion of the work, the joint is rendered substantially invisible.

When a conventional blade is used, it is commonly drawn transversely of the joint, and as a result, ridges are left throughout the length of the joint, which are difiicult to sand down.

It is, accordingly, the main object of the present invention to provide a joint blender which is so formed as to have means embodied therein adapted not only for retaining the blade in a normally flat condition, but also adapted for bowing the blade transversely whenever desired, thus to impart a curvature to the joint finishing edge of the blade, which curvature will be transmitted to the cementitious joint throughout the length of said joint.

Another important object is to provide a tool of the character referred to wherein the means employed for bowing the blade transversely will be brought into operative relation to the blade portion of the tool merely by exertion of pressure, in the direction of the cementitious joint, against the handle of the tool.

Yet another object of importance is to provide a tool as described wherein the above stated, desirable results will be obtained, while at the same time permitting the tool to be manufactured at a nominal cost, thus to bring it within the reach of the ordinary home owner, who uses a tool of the type stated only at comparatively rare intervals.

Still another object is to provide a tool as stated, wherein the means embodied therein for bowing the blade transversely will be so designed as to act efficiently when brought into use, even though the tool may be in the hands of a comparatively unskilled worker.

Other objects will appear from the following description, the claims appended thereto, and from the annexed drawing, in which like reference characters designate like parts throughout the several views, and wherein:

Figure 1 is a top plan view of a tool formed in accordance with the present invention, a pair of adjacent structural panels, and a cementitious joint bonding adjacent edges of said panels, being illustrated fragmentarily;

Figure 2 is a side elevational view of the tool as it appears when it is in use, the dotted lines illustrating the normal position of the parts, in which the blade of the tool is flat, and the full lines illustrating a position of the parts effective to how the blade transversely, the building wall to which the tool is applied being illustrated in vertical section;

Figure 3 is a transverse sectional view taken on line 3-3 of Figure 1; and

Figure 4 is a perspective view of the tool per se.

Referring to the drawings in detail, the reference numeral 10 has been applied to a pair of side-by-side structural panels, adjacent edges of which are spaced apart as at 12. Cementitious material 14 is applied to said panels, said material being coated upon the adjacent edge portions of the panels and filling the space 12 between said adjacent edge portions. It will be understood, in this connection, that if desired, a perforated building tape can be used with the joint cement 14, the tool constituting the present invention being so designed as to be capable of eflicient use whether or not a tape of this type is employed.

In using a cement 14, it is the customary practice to first plaster said cement on in a substantially flat condition, after which the' cement is given a transverse convexity, so as to feather out the opposite longitudinal edges of the cementitious joint.

In this connection, the tool which I have designed is so formed as to be usable first, for plastering on the cement in a substantially flat condition, and second, for imparting the desired transverse convexity to the cement.

The tool, in this regard, includes a handle member designated generally by the reference numeral 16, and a blade carried by said handle member and designated generally by the reference numeral 18. These will be described in turn.

Considering first the construction of the handle member 16, said handle member includes an elongated handle 20 which can be formed of wood, plastic, or other material and having a pressure arm 26 at one end and a spring portion or shank 22 at the opposite end, said handle having rounded ends in the illustrated embodi' ment of the invention and affording a grip for a user.

Embedded in the handle 20 is a spring shank 22. The spring shank 22 is of arcuate formation, as readily seen from either Figure 2 or Figure 4, said shank being curved longitudinally so as to dispose the other end of the shank under and in spaced relation to the handle 20.

Said other end of the shank is flattened as at 24, and rivets or other fastening elements are employed for securing the flattened end 24 to the apex end of the blade 18.

To the other end of the handle 20 there is fixedly secured one end of a pressure arm 26, said arm being rela tively short and relatively curved longitudinally. It may be noted, in this connection, that the pressure arm 26, the handle 20, and the spring shank 22 are all aligned longitudinally, as best shown in Figure 1.

The pressure arm 26 extends downwardly from the handle 20, in the direction of the broad end of the blade 18, and secured fixedly to that end of the pressure arm remote from the handle 20 is the intermediate portion of a cross head 28 carried by the pressure arm. The cross head 28 is disposed transversely of the body and of the blade 18, and is extended in parallelism with the plane of the normally flat blade 18.

The cross head 28 is of inverted U-shaped formation, and is integrally formed, at its opposite ends, with depending fingers 30, said fingers being normally spaced from the blade 18 as shown by the dotted line position of the fingers in Figure 2.

The blade itself is fashioned from a single piece of flat material capable of being springably flexed transversely; and 'metal, plastic, or any other material having--thedesiredspringable characteristics canbe -em ployed. In this connection, the blade 18 is of approximately triangular shape, having side edges 32 converging toward'one end of the blade to point the blade at said one-end.- Thepointed end of the blade is securedifixedly to the flattened end24 of the springshank, 22;

At the other end of the blade 18,,there is provided 'a straightjoint finishing edge 34,- said edge being disposed transversely of the blade and body, in parallelism with tliebight of the cross head-28:

In use, the blade 18 will normallybe flat, as shownin Figure 4, and: in this position of the parts, the. tool is employed for coatingthe jointcement 14" upon :the panels*10 in such a manner as to applyaflat coat of cement to-saidpanels.

Subsequently,- when it is desired to convex thejoint transversely-gtliereof, the user need'merely'exert a pressure-upon=the handle 20, inthe direction of the joint, as-aresultof which the pressure arm'26, and the cross head-28', will be shifted'to the-full line position thereof shown: in Figure 2, against the spring action of the shank 22 Asa result; the fingers 30 will be caused to engageth'e, opposite side edge portions of the blade. 18, adjacent the joint finishing edge, and the 'result'will be that :thezbladelS- will be=curved:transversely; as shown in Figure:- 3.

The blade'18 is aided in itsspringable flexure to a transversely curvedcondition by the joint cement itself, said cement resisting movement of the blade toward the space;12 ;.alongthe longitudinal center line of the blade, but 'offering no=resistance=to movement of the side edges of the blade against the panels 10, since the cement is free-to-fiow; outwardly or inwardly from said side edge portions ofthe blade when the side edge portions. are forced toward' the panels.

It is'believed apparent that the invention isnot necessarily confined to the specific use or uses thereof described above, since it may be utilized for any purpose to'which-it-'may"be suited Nor is" the" invention to"be' necessarily limited to the specific construction illustrated and described, since such construction is only intended to be illustrative of the principles of operation and the means presently devised to carry out said principles, it being considered that the invention comprehends any minor change in construction that may be permitted within the scope of the appendedclaims.

What is claimed is:

1. A trowel comprisingya substantially triangular flexible blade having,two,v equal, converging. sides, a substantially arcute handle member'having a pressure arm at one end and a spring;por,tion. at.theopposite end secured to the apex of said converging sides, a handle on said handle member, a crosshead on the end of said pressure arm, and a depending finger afiixed to each end of the crosshead and normally spaced from the blade whereby'pressure on said'handl'e will bring the pressure fingers'into contact with'the 'side' edges of'the blade to flex the blade on' a'longitudinal axis around a mortar joint.

2. A-trowehcomprisinga flexible blade, a handle member centrally disposed above said blade and secured pressure on said handle member'willtend 'to' bow said blade about amortar joint;

References Cited in the file-of this patent UNITED STATES PATENTS" 1,083,099 Howg Dec. 30,- 1913 1,956,370. Ameer= Apr. 24, 1934 1,999,367 McCorkle A nao, 1935 2,535,568.,

Crippen Dec. 26, 1950 

